As a layperson with an interest in speciation I want to present my definition of Sexual Reproduction.Every species can be defined by the haploid ovum (complete set of chromosomes = n ), humans having 23. This is the new individual at the start of its life cycle. Billions of such species still exist. However, the next stage, if the species is multi-celled is the 2n time, when cells are given a second, matching set. This is achieved by the arrival of a sperm, which is not a complete cell, but a nucleus with one, matching set. When it enters an egg, it undergoes simultaneous meiosis with the egg's set. As soon as the zygote is formed millions of new eggs are made, to await their chances of 2n in the ovary.Sexual Reproduction is not a mixing (recombination is for physical arrangements of the chromosomes) but the addition of the second set for somatic cells, just a part of the life cycle.

I have received an answer from a Professor of Biology that says 'species are populations of similar individuals and not cells, be they egg or sperm, produced by these individuals. This obviates my theory, that every individual of any species starts as a single cell, the haploid egg, n, with a single, complete set of chromosomes in its nucleus (humans 23) and a 2n part of the life cycle when sperm add the second, complete and matching set ('fertilization') so that somatic cells can make organs for a 'body'. What do you think? Is my theory better than the Professor's?